Notifications missing-Tab 10.1Support

I have a galaxy tab 2, 10.1 (model number GT-P5113, android version 4.0.4).
Up to maybe 2 weeks ago it showed all the notification available......facebook, gmail, app updates, games installed reloaded......but now it doesn't show any facebook notifications, and no "app updates available" notifications.
The notification options is green and active.

Sound as if your "notifications" are turned off.
Tap the clock to open the system box, in that box you will find a row of icons that that you can scroll through. Tap the Notifications icon to turn on Green is on: grey id off